The present invention relates to sewing machines for embroidering/sewing patterns onto curved surfaces, such as peripheral surfaces of crowns of headwear or hats. More particularly, the present invention relates a sewing machine including a means for correcting embroidery or sewing data in accordance with an embroidering or sewing workpiece, as well as a data creation apparatus, sewing method and program usable for such a sewing machine.
When embroider a substantially-cylindrical embroidering workpiece, such as a hat, it has been conventional to detachably attach a cylindrical embroidery frame (e.g., cap or hat frame), having the embroidering workpiece set thereon, to a drive ring that is driven rotationally and linearly along a rotation axis in accordance with a desired embroidery pattern. FIG. 8 is a perspective view showing an outer appearance of an example of a conventional single-head compact sewing machine to which a cap frame is attachable. Machine head 1 is provided with a plurality of sewing needles to permit a selection from among a plurality of thread colors. Beneath the machine head 1, there are provided a drive ring 2 that is driven rotationally and linearly along a rotation axis in accordance with a desired embroidery pattern, and a support plate 3 that is fixed within an interior space of the drive ring 2 for supporting an embroidering workpiece from below the workpiece at a needle drop location (i.e., sewing position). Rotary hook base (not shown) is provided beneath the support plate 3. FIG. 9 is an enlarged view showing the drive ring 2 and support plate 3, as well as a cap frame 4 detachably attached to the drive ring 2. The drive ring 2 is reciprocatively rotated via a transmission wire 23 in response to reciprocative linear movement, in an X-axis direction, of an X-axis drive plate 21, and it is also reciprocatively moved along a rotation axis in response to reciprocative linear movement, in a Y-axis direction, of a Y-axis drive plate 22. As know in the art, the X-axis and Y-axis drive plates 21 and 22 are driven in accordance with desired embroidery pattern data.
The cap frame 4 includes a cylindrical supporting frame section 41 on which an opening (free end) portion of the hat (in this case, cap) is placed and set, and a band-shaped pressing frame section 42 for pressing the periphery of the opening portion of the cap against the supporting frame section 41 to thereby hold the cap. In the illustrated example of FIG. 9, the supporting frame section 41 has a free end 41a that forms a plane perpendicular to a horizontal rotation axis of the supporting frame section 41; that is, the free end 41a of the supporting frame section 41 agrees with a rotational circumferential direction of the cap frame 4. FIG. 10 is a side view showing the cap frame 4, having the cap C set thereon, attached to the drive ring 2. The opening (free end) portion of the cap C is set along the free end 41a of the supporting frame section 41 and then pressed by the band-shaped pressing frame section 42 radially inward from outside the opening portion. In this manner, the cap C can be set in such a manner that its opening (free end) portion agrees with the rotational circumferential direction of the cap frame 4, i.e. with no inclination angle relative to a plane perpendicular to the rotation axis of the cap frame 4. Such a type of cap frame is disclosed in, for example, Japanese Patent Application Laid-open Nos. HEI-2-251660, HEI-8-209523 and 2001-17760(herein after referred to as patent literatures 1, 2 and 3, respectively).
As a recent trend of the shape of caps, there have been marketed caps having a crown narrowing to the top in a cone shape as compared to the traditional cylindrical crown as depicted in FIG. 12 by a phantom line C′. If such a type of cap (hereinafter referred to as “new-type cap”) C is embroidered by being set on the conventional cap frame 4 as shown in FIG. 10, desired embroidery can not be performed nicely due to various problems as set forth below. Namely, the new-type cap C can keep a conical inclination, as indicated by a two-dot-dash line, when the new-type cap C is set on the cap frame 4 alone. However, when the cap frame 4 with the cap C set thereon is attached to the drive ring 2, a near-top region of the peripheral surface of the cap crown is strongly pressed against the front edge of the support plate 3 so that the near-top region of the peripheral surface of the cap crown is forced radially outwardly. Thus, when the cap frame 4 is being driven to rotate, the cap fabric tends to be prevented from moving smoothly with the rotating cap frame 4 due to contact resistance between the inner surface of the cap C and the support plate 3, which would often cause a thread breakage and prevent an embroidery pattern from being made as indicated by embroidery data. Such problems would sometimes result in defective products.
Further, in performing embroidery on a region of the new-type cap C adjacent to the base of a visor (i.e., region indicated by an arrow P in FIG. 10), the cap frame 4 is pushed out toward the front (in a Y direction in FIG. 1) together with the drive ring 2. At that time, the visor of the new-type cap C, pushed out toward the front together with the cap frame 4, contacts a guide plate 6 that is provided to buffer abutment of the visor against the rear surface of a machine arm 5, so that contact resistance between the visor and the guide plate 6 too would adversely influence the sewing. If the visor of the cap C is inclined away from the guide plate 6 instead of extending upward in contact with the guide plate 6 as shown in FIG. 10, the aforementioned inconvenience can be avoided; however, the conventional techniques shown in patent literatures 1-3 identified above are not so arranged.
Japanese Patent Application Laid-open Publication No. HEI-7-238465 (patent literature 4) discloses a technique where the free end of the supporting frame section of the cap frame for holding the new-type cap C is inclined in conformity with an inclination angle δ of the peripheral surface of the crown of the cap C as illustrated in FIG. 11. With such an inclination, the visor of the cap C can be positioned away from the guide plate 6 instead of extending upward in contact with the guide plate 6 as shown in FIG. 10. Because the visor of the cap C can be thus prevented from contacting the guide plate 6, the technique disclosed in patent literature 4 can avoid the aforementioned inconvenience.
However, with the technique disclosed in patent literature 4, desired embroidery sewing is performed on the peripheral surface of the crown of the new-type cap C, set on the cap frame with its visor inclined, in accordance with embroidery data created on the assumption that the visor is not inclined. Thus, an embroidery pattern formed on the cap as a result of the sewing (i.e., sewn embroidery pattern) would have unwanted deformation. Namely, if an embroidery pattern comprising a horizontal straight string of letters as illustrated in (a) of FIG. 7 is sewn onto the peripheral surface of the crown of the new-type cap C, set on the cap frame with its visor inclined, in accordance with the embroidery data created on the assumption that the visor is not inclined, then the sewn embroidery pattern would be undesirably curved or deformed as illustrated in (b) of FIG. 7.